Idler-roller recoil device

Abstract

An idler recoil device (10) is utilized for track-type vehicles. The idler recoil device (10) protects a crawler track system (11) from damage when some foreign object, such as a rock, is trapped between an endless chain link assembly (28) and a chain supporting element (20,22,24,26) of the crawler track system (11). An idler link (30) is pivotally connected to a track frame (12) of the crawler track system (11) and a recoilable rear idler (24) is rotatably positioned on an idler hub (54) itself pivotally connected to said idler link (30). An increase in tension on said endless chain link assembly (28) causes said idler hub (54) to rotate away from said endless chain link assembly (28) decreasing track path length and, consequently, tension. This rotation is resiliently resisted by a recoil pad (66) mounted between said idler hub (54) and said idler link (30). A tensile link (68) prevents any recoil up to a preselected endless chain link assembly (28) tension.

I claim: 
     
       1. An idler recoil device (10) adapted for use in a crawler track system (11) having a track frame (12), comprising: an idler link (30) having a first end portion (32), a center portion (48), and a second end portion (34), the first end portion (32) being bifurcated to form a first extension (40) and a second extension (42), said idler link (30) being pivotally connected to said track frame (12);   an idler hub (54) pivotally connected to said second extension (42);   an idler (24) rotatively mounted on said idler hub (54);   first resilient means (66) for biasing said idler (24) outwardly from said first extension (40), said first resilient means (66) being positioned between said first extension (40) and said idler hub (54);   second resilient means (90,92) for resiliently resisting upward movement of the idler link second end (34); and   third resilient means (82,84,88) for resiliently resisting downward movement of the idler link second end (34).   
     
     
       2. The idler recoil device (10) of claim 1 further comprising a roller assembly link (82) pivotally connected to the track frame (12) and extending in a direction away from said idler link first end portion (32) and being substantially beneath said idler link second end portion (34), there being a roller assembly (84) connected to said roller assembly link (82), and wherein said third resilient means (82,84,88) includes an elastomeric element (88) positioned between the idler link second end portion (34) and said roller assembly (84). 
     
     
       3. An idler recoil and track support device (10) adapted for use in a crawler track system (11) having a track roller frame (12), comprising: an idler link (30) having a first end portion (32), a center portion (48) and a second end portion (34), said idler link (30) being pivotally connected to said track roller frame (12) by a pin (50);   an idler hub (54) pivotally connected to said idler link first end portion (32);   an idler axle (60) connected to said idler hub (54);   an idler (24) connected to said idler axle (60) and being rotatable relative to said idler hub (54);   means (66) for biasing said idler hub (54) for rotation away from said idler link pin (50) such that said idler (24) is outwardly biased from said idler link (30); and   means (82,84,88) for resiliently resisting upward rotation of said idler link first end portion (32).   
     
     
       4. The idler recoil and track support device (10), as set forth in claim 3, wherein said pin (50) is positioned at said idler link center portion (48). 
     
     
       5. The idler recoil and track support device (10), as set forth in claim 4, wherein said means (82,84,88) for resiliently resisting upward rotation of said idler link first end portion (32) includes: a roller assembly link (82) pivotally connected to the track frame (12); a roller assembly (84) attached to said roller assembly link (82); said roller assembly (84) being positioned substantially beneath said idler link second end portion (34); and, a resilient element (88) interposed between said idler link second end portion (34) and said roller assembly (82). 
     
     
       6. The idler recoil and track support device (10), as set forth in claim 5, further including means (90,92) for resiliently resisting upward rotation of said idler link second end portion (34). 
     
     
       7. An idler recoil device (10) adapted for use in a crawler track system (11) having a frame (12), comprising: an idler link (30) having a first end portion (32), a second end portion (34) and a center portion (48), the first end portion (32) having a first extension (40) and a second extension (42), said idler link (30) being pivotably connected to said frame (12) by a track frame pin (50) passing through said idler link center portion (48);   an idler hub (54) pivotally connected to said second extension (42);   an idler (20,24) rotatively connected to said idler hub (54);   first means (66) for biasing said idler hub (54) away from said first extension (40); and   a roller assembly link (82) pivotally connected to said frame (12) and extending generally beneath said idler link second end portion (34), said roller assembly link (82) and said idler link second end portion (34) being in force transmitting relationship one to the other.   
     
     
       8. The idler recoil device (10) of claim 7 further comprising a resilient element (88) positioned intermediate said roller assembly link (82) and said idler link second end portion (32). 
     
     
       9. The idler recoil device (10) of claim 7 or claim 8 further comprising a stop member (90) rigidly connected to said frame (12) at a position substantially above said idler link second end portion. 
     
     
       10. The idler recoil device (10) of claim 9 further comprising a resilient mens (92) interposed between said stop member (90) and said idler link second end portion (34). 
     
     
       11. In a crawler track system (11) having: a track frame (12) having a fore portion (14), an aft portion (16) and a center portion (18);   at least one track roller assembly (22) connected to said track frame (12);   an idler (20/24) connected to the track frame (12); and   an endless track assembly (28) adapted to be driven by a drive sprocket (26), said endless track assembly (28) being trained about said idler (20/24), said drive sprocket (26) and said track roller assembly (22), the improvement comprising:   an idler link (30) pivotally connected to said track frame (12), said idler link (30) having a first end portion (32), a center portion (48), and a second end portion (34), the first end portion (32) being bifurcated to form a first extension (40) and a second extension (42);   an idler hub (54) pivotally connected to said second extension (42);   an idler axle (60) mounted on said idler hub (54);   said idler (20/24) being rotatively mounted on said idler axle (60); and   first resilient means (66) positioned between said first extension (40) and said idler hub (54) for permitting recoil of said idler (20/24).   
     
     
       12. The crawler track system (11), as set forth in claim 11, further including means (82,84,88) for resiliently resisting upward movement of said idler link first end portion (32). 
     
     
       13. The crawler track system (11), as set forth in claim 11, further including means (90,92) for resiliently resisting downward movement of said idler link first end portion (32). 
     
     
       14. The crawler track system (11), as set forth in claim 13, further including a pivot pin (50), said pivot pin (50) being mounted on said track frame (12), said idler link (30) being connected to said pivot pin (50) at said idler link center portion (48). 
     
     
       15. The crawler track system, as set forth in claim 14, wherein said downward movement resisting means (90,92) includes a stop (90) connected to said frame (12), said stop (90,92) being positioned above said idler link second end portion (34). 
     
     
       16. The crawler track system, as set forth in claim 15, further including a roller assembly link (82) pivotally connected to said track frame (12), said roller assembly link (82) having a roller assembly (84) attached thereto, said roller assembly (84) being substantially beneath said idler link second end portion (34). 
     
     
       17. The crawler track system, as set forth in claim 16, further including a resilient element (88) interposed intermediate said idler link second end portion (34) and said roller assembly (82). 
     
     
       18. The crawler track system, as set forth in claim 14, wherein said track assembly (28) and idler (20/24) define two bounds of track-idler contact (72), said bounds of track-idler contact (72) defining two tangents to said idler (20/24) at said bounds of track-idler contact (72), there being a bisector (70) of said tangents, said idler axle (60) and said pivot pin (50) both being positioned such that said bisector (70) passes substantially through said idler axle (60) and said pivot pin (50).